RFID methods are widely used in a number of applications, including smart cards, item tracking in manufacturing and retail, etc. An RFID tag can be attached to an object, such as a retail item. An encoded information reading (EIR) terminal deployed at the cashier's desk can be equipped with an RFID reader to read and/or modify the memory of an RFID tag attached to a retail item. However, the antenna of the RFID reader may be susceptible to environments and may not have a broad bandwidth. A small environmental factor (e.g., hand position on the terminal, etc.) may shift the band off targeted frequency, and greatly downgrade the performance.